Engine for low-temperature expansion.



UNITED STATES PATENT OFFICE.

EBEINEZER A. W. JEFFERIES, OF WORCESTER, MASSACHUSETTS, ASSIGNOR TOJEFFERIES-NORTON CORPORATION, OF WORCESTER, MASSACHUSETTS, A COR-PORATION OF DELAWARE.

ENGINE FOR LOW-TEMPERATURE EXPANSION.

Specification of Letters Patent.

Patented Apr. 30, 1918.

Application filed December 1, 1915, SerialNo. 64,420. Renewed January19, 1918. Serial No. 212,852.

To all whom it may concern:

Be it known that I, Esnnnznn A. W. JEF- FEnrns, a citizen of the UnitedStates, residing at Worcester, in the county of Worcester andCommonwealth. of Massachusetts, have invented a new and usefulImprovement in Engines for Low-Tem erature Expansion, of which thefollowing, together with the accompanying drawing, is a specification.

The resent invention relates to improvements in engines used to expandgases to extremely low temperatures, as, for instance, engines of theclass known as cold expansion engines which are employed in theliquefaction of air and other gases. My invention is particularlyadapted for use in connection with a piston equipped cylinder in whichcompressed air or other gas, at a low temperature, is still furtherreduced in temperature, for refrigeration purposes, b expension, and atthe same time is ma e to expend its ener in producing useful work.

In such engmes, of course, ideal conditions of operation are attainedwhen the difference in temperature between the relatively warm gasadmitted to the cylinder and the cold gas exhausted from the cylinder isa mammum. In other words, the efiiciency of such engines is dependentupon the attainment of e lowest ossible temperature of the gas exhaustedmm the cylmder. When the gas is surrounded by ordinary metallic cylinderwalls, a large amount of heat is absorbed during the admission ofthe'relatively warm compressed gas to the cylinder; upon expansion ofthe gashaccompanied by a drop in temperature, t is heat absorbed by thecylinder walls is given up to the expandin gas, with the result that thetheoretical rep in temperature is not attained. With the use of internalmetallzic surfaces therefore, as in all engines of this class now inuse, the above described interch e of heat between the gas and themetal, uring the wide ranges of tempera ture change which occur,seriousl impairs the efliciency of such engines. hats to say, the greatamount of heat stored in the metal at each influx of relativel warm gasto the cylinder has the efi'ect o greatly diminishing the natural dro intemperature due to expansion, thus do eatin to a considerable extent,the object soug t to be attained. It is to be understood that the actionabove described is wholly internal, applying only to changes oftemperature oc curring within the cylinder, as distinguished from theproposition of insulating the 0 lim der walls from external atmosp ericcat, which, of course, can be accomplished in the ordinary way byexterior insulating ma.- terial, to preventthe passage of heat throughsaid walls.

7 The principal object of the present invention is to provide, inengines of the class specified, a suitable interior covering for themetallic inclosing surfaces which would otherwise be in contact with thegas during its expansion. By the provision of a covering 0 low heatcapacity, the losses due to the alternate abSOIEHSlOD and rejection ofheat by the cylin er walls, as above described, are greatly reduced,since the amountof heat so absorbed and rejected will be very rbe smallas com ared to the amount abso and rejected y metallic cylinder walls.It is well known that in ordinary expansion cylinders operating at verylow temperatures, that is, temperatures below minus two hundred degreesFahrenheit, the drop in temperature due to expansion seldom attains morethan forty per cent. of the natural or calculated range which should beobtained under perfectly isentropic conditions. On the other hand, in anengine having its gas contacting surfaces equipped with a covering inaccordance with my invention, the actual drop in temperature exceeds inpractice eight per cent. of the theoretical temperature ro this actionnot only increases the eflicienc of the engine, but results in othervalue le advantages in that it permits the use of lower pressures toobtain the same degrees of cold, thereb greatly simplifyin theconstruction an such re rigeratin machinery an other apparatus for theliquefaction of fluids which are gaseous in their free states.

In the accompanying drawings I haverepresented my invention as a pliedto a piston equipped cylinder adap to be used in connection with theliquefaction of air or other gases.

In said drawings, Figure 1 represents in longitudmalsectmn a piston equpped cylinder embodying my invention.

0 eration of all F1 2 is a transverse sectionarview on the turesprevailing in refrigeration and lique-" faction systems. A piston 2within the cylinder 1 is operatively connected in the usual manner withanysuitable mechanism, not shown, to which the energy imparted to thepiston is transferred. y

The cylinder 1 has an inlet port 3,

;through which the charge of compressed air,

application above by lin or other gas,'at low temperature, is admitted,when the piston 2vis at the extreme end of its inward movement. Thecompressed air or other gas within the cylinder 1s then allowed toexpand against the piston to force. the latter outwardly, thereby reducig the temperature of the gas and utilizing its expansive energy toperform useful work. When the limit of expansion is reached, the gas isexhausted through the outlet port 4 and. being at a lower temperaturethan its admission temperature, is available for refrigeration purposes,in the usualmanner.

ccordin to my invention, the cylinder 1 consists o a metal shell 5,havin an inner linin 6 of low heat ca acity. e lining which I employ,and w 'ch constitutes the essential feature of the present invention,consists princi ally of fibrous material, such as paper, woo fiber, orasbestos fiber, 8111bably compounded with a strong binder, such asbakel1te, and, if desired, with a small amount of graphite, and thenmolded into rings 7, 1m er high pressure, and with the of sufiiclentheat to set the binder. I may make such a lining as described I ghlnargenumbers of thin annuli, made-of o ary Manila drawing aper, upon a hollowmandrel, whose outer meter is slightly loss than the diameter of theis'ton 2. Befoiethese annullifiare-assemble on the mandrel, they ai -e1with a binder, for example liquid' 'baliblite, and one surface may berinkled with powdered graphite. The ho ow mandrel is then heated byputting its interior s' ace under steam ressure, and the bl annuli' areress f down upon each other with orce, either in a hydraulic press or byorcing metal rings on the ends of the mandrel toward each other with aseries of bolts. The reat pressure forces out the superfluous bakefiteso that none of it remains except a binding film between each layer ofpaper. The heat and pressure is maintained for at least twenty-fourhours, at the end of which time the materials, namely paper, graphiteand binder, have become incorporated into a I above described,

- the latter is not essentia am also aware that it has been solid mass.The steam is exhausted from the mandrel, which cools and allows themass, in the form of a ring, to be withdrawn easily. The ring so formedconsists principally of compressed paper fiber, which is easily turnedand bored in a lathe and then presents a smooth, dense, black surface ofvery small heat capacity, practically selflubricating, and having thepeculiar property of becoming stronger and more tenacious when subjectedto extreme cold a property not possessed by compound substancesconsisting ,principally cf. graphite, or those which have not beenformed y great pressure under the influence of heat.

Such rin may be made of any predetermined thickness and forced into themetal shell 1 to line the same from end to end.

While I have described one method of malnng the rings 7 used for liningthe metal shell, it is to be understood that 'I am not limited to theabove or any other method of making the lining; obviousl the purposesposed principally of fiber, and a suitable binder, with or withoutstances bein compounds under high pressure and wifii the prolongedapplication of sufiicient heat.

The head 8 of the cylinder is preferably provided also with a similarfibrous plate or covering 9, attached thereto in any suitable manner andhaving the peculiar properties its constituent substancesbeing'compounded under pressure and with the application of heat. Thehead of the piston or lunger 2 is similarly faced with afibrous p ate orcovering 10, attached there to in any suitable manner, made insubstantially the same way, and if desired, the periphery of the piston2 may have anexternal covering 11'of the same roperties, although smcethe lining 6, and plates 9 and 10, furnish under all cir-.

cumstances surfaces of low heat capacgy' completely surroundingthe gasesadmi to the engine. a

I am' aware that linings for cylinders have previously been suggested,composed principally of graphite, in order to avoid the use of ordinaryunctuous lubricants, and especially designed to be used with motivefluids w 10h destroy such lubricants, and I roposed to mold suchgraphite into a suite 1e mass by compounding it with 'fiber or the like.Therefore, I make no claimtosuch a lining which, ObVlOllSli, is whollyunsuited for the particular use escribed above, as

im is a substance having oonsiderable'i ez t capacity and small cohesivestrentfith. My 'inventlon resides primarily inv e discovery that a linincomposed princi ally of fiber, compounde with a suitable inder preferphite the subabove, and it is this ably under high pressure and with theprolonged application of suflicient heat, with or without the additionof aphite, has its strength and permanence of form, and also itstenacity and durability greatly increased at the extremely lowtemperatures to which it is subjected in the particular use describedproperty which is essential to the purposes of my invention. Any lininwhich consists principally of graphite, or w ich is compounded in theabsence of great pressure, accompanied by heat, or in which anunsuitable binder, such as water with a small percentage of fiber,'isemployed, does not have these properties, and does not moreover attainto t em, even under the influence of intense cold, in such render thesubstance suitable poses which I have described.

Obviously, as I have stated, the graphite, which may or may not be usedin the compound, as desired, is in no way contributory to the attainmentof my principal object, but is incorporated for the obvious purpose ofproviding as far aspossible a self-lubricating surface, against whichthe piston 2 can move with minimum friction.

I claim 1. In a device of the a. cylinder for the expansion ofgasesat'extremely low temperatures, comprising a metallic shell orcasing having a lining of low heat capacity, whereby the interchange ofsubstantial quantities of heat between degree as to for the purcharacterdescribed,

the gas and the surfaces with which it is in tact during expansion isprevented, said lining consisting principally of fibrous material,compounded with a strong binder by the application of pressure and heat.

In a device of the character described, a cylinder for the expansion ofgases at extremely low temperatures, com rising a. metallic shell orcasing having a ining of low heat capacity, whereby the interchange ofsubstantial quantities of heat between the gas and the surfaces withwhich it is in contact during expansion is prevented, said liningincreasing in hardness and tenacity when subjected to the extremel lowtemperatures prevailin in said cy inder, and consistin princi a y offibrous material compoun ed wit a small percentage 0% graphite and abinder, by the application of eat and pressure.

3. In a device of the character described, a cylinder for the expansionof compressed fluids which are gaseous in their free state and whichhave been the production of extreme cold, comp a metallic shell orcasing having a lining o low heat capacity, whereb of substantialquantities of cat by said shell from the incoming compressed fluid isprevented, said lining consistin principally of fibrous materialcompound with a binder.

EBENEZER A. W. JEFFERIES. Witnesses:

rm Coon, Nnnnm Wmmm.

the absorption previously cooled, for

